On Sat, Jun 20, 2020 at 07:16:16PM -0700, Andrew Morton wrote:
> On Thu, 18 Jun 2020 08:43:06 +0200 Christoph Hellwig <hch@xxxxxx> wrote:
>
> > Use PAGE_KERNEL_ROX directly instead of allocating RWX and setting the
> > page read-only just after the allocation.
> >
> > --- a/arch/arm64/kernel/probes/kprobes.c
> > +++ b/arch/arm64/kernel/probes/kprobes.c
> > @@ -120,15 +120,9 @@ int __kprobes arch_prepare_kprobe(struct kprobe *p)
> >
> > void *alloc_insn_page(void)
> > {
> > - void *page;
> > -
> > - page = vmalloc_exec(PAGE_SIZE);
> > - if (page) {
> > - set_memory_ro((unsigned long)page, 1);
> > - set_vm_flush_reset_perms(page);
> > - }
> > -
> > - return page;
> > + return __vmalloc_node_range(PAGE_SIZE, 1, VMALLOC_START, VMALLOC_END,
> > + GFP_KERNEL, PAGE_KERNEL_ROX, VM_FLUSH_RESET_PERMS,
> > + NUMA_NO_NODE, __func__);
> > }
> >
> > /* arm kprobe: install breakpoint in text */
>
> But why. I think this is just a cleanup, doesn't address any runtime issue?
It doesn't "fix" an issue - it just simplifies and speeds up the code.
